timerx8.c

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/*! \file timerx8.c \brief Timer function library for ATmegaXX8 Processors. */
//*****************************************************************************
//
// File Name    : 'timerx8.c'
// Title        : Timer function library for ATmegaXX8 Processors
// Author       : Pascal Stang - Copyright (C) 2000-2005
// Created      : 11/22/2000
// Revised      : 06/15/2005
// Version      : 1.0
// Target MCU   : Atmel AVR Series
// Editor Tabs  : 4
//
// This code is distributed under the GNU Public License
//      which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <avr/sleep.h>

#include "global.h"
#include "timerx8.h"

// Program ROM constants
// the prescale division values stored in order of timer control register index
// STOP, CLK, CLK/8, CLK/64, CLK/256, CLK/1024
unsigned short __attribute__ ((progmem)) TimerPrescaleFactor[] = {0,1,8,64,256,1024};
// the prescale division values stored in order of timer control register index
// STOP, CLK, CLK/8, CLK/32, CLK/64, CLK/128, CLK/256, CLK/1024
unsigned short __attribute__ ((progmem)) TimerRTCPrescaleFactor[] = {0,1,8,32,64,128,256,1024};

// Global variables
// time registers
volatile unsigned long TimerPauseReg;
volatile unsigned long Timer0Reg0;
volatile unsigned long Timer2Reg0;

typedef void (*voidFuncPtr)(void);
volatile static voidFuncPtr TimerIntFunc[TIMER_NUM_INTERRUPTS];

// delay for a minimum of <us> microseconds 
// the time resolution is dependent on the time the loop takes 
// e.g. with 4Mhz and 5 cycles per loop, the resolution is 1.25 us 
void delay_us(unsigned short time_us) 
{
    unsigned short delay_loops;
    register unsigned short i;

    delay_loops = (time_us+3)/5*CYCLES_PER_US; // +3 for rounding up (dirty) 

    // one loop takes 5 cpu cycles 
    for (i=0; i < delay_loops; i++) {};
}
/*
void delay_ms(unsigned char time_ms)
{
    unsigned short delay_count = F_CPU / 4000;

    unsigned short cnt;
    asm volatile ("\n"
                  "L_dl1%=:\n\t"
                  "mov %A0, %A2\n\t"
                  "mov %B0, %B2\n"
                  "L_dl2%=:\n\t"
                  "sbiw %A0, 1\n\t"
                  "brne L_dl2%=\n\t"
                  "dec %1\n\t" "brne L_dl1%=\n\t":"=&w" (cnt)
                  :"r"(time_ms), "r"((unsigned short) (delay_count))
    );
}
*/
void timerInit(void)
{
    u08 intNum;
    // detach all user functions from interrupts
    for(intNum=0; intNum<TIMER_NUM_INTERRUPTS; intNum++)
        timerDetach(intNum);

    // initialize all timers
    timer0Init();
    timer1Init();
    #ifdef TCNT2    // support timer2 only if it exists
    timer2Init();
    #endif
    // enable interrupts
    sei();
}

void timer0Init()
{
    // initialize timer 0
    timer0SetPrescaler( TIMER0PRESCALE );   // set prescaler
    TCNT0 = 0;                              // reset TCNT0
    sbi(TIMSK0, TOIE0);                     // enable TCNT0 overflow interrupt

    timer0ClearOverflowCount();             // initialize time registers
}

void timer1Init(void)
{
    // initialize timer 1
    timer1SetPrescaler( TIMER1PRESCALE );   // set prescaler
    TCNT1 = 0;                              // reset TCNT1
    sbi(TIMSK1, TOIE1);                     // enable TCNT1 overflow
}

#ifdef TCNT2    // support timer2 only if it exists
void timer2Init(void)
{
    // initialize timer 2
    timer2SetPrescaler( TIMER2PRESCALE );   // set prescaler
    TCNT2 = 0;                              // reset TCNT2
    sbi(TIMSK2, TOIE2);                     // enable TCNT2 overflow

    timer2ClearOverflowCount();             // initialize time registers
}
#endif

void timer0SetPrescaler(u08 prescale)
{
    // set prescaler on timer 0
    TCCR0B = ((TCCR0B & ~TIMER_PRESCALE_MASK) | prescale);
}

void timer1SetPrescaler(u08 prescale)
{
    // set prescaler on timer 1
    TCCR1B = ((TCCR1B & ~TIMER_PRESCALE_MASK) | prescale);
}

#ifdef TCNT2    // support timer2 only if it exists
void timer2SetPrescaler(u08 prescale)
{
    // set prescaler on timer 2
    TCCR2B = ((TCCR2B & ~TIMER_PRESCALE_MASK) | prescale);
}
#endif

u16 timer0GetPrescaler(void)
{
    // get the current prescaler setting
    return (pgm_read_word(TimerPrescaleFactor+(TCCR0B & TIMER_PRESCALE_MASK)));
}

u16 timer1GetPrescaler(void)
{
    // get the current prescaler setting
    return (pgm_read_word(TimerPrescaleFactor+(TCCR1B & TIMER_PRESCALE_MASK)));
}

#ifdef TCNT2    // support timer2 only if it exists
u16 timer2GetPrescaler(void)
{
    //TODO: can we assume for all 3-timer AVR processors,
    // that timer2 is the RTC timer?

    // get the current prescaler setting
    return (pgm_read_word(TimerRTCPrescaleFactor+(TCCR2B & TIMER_PRESCALE_MASK)));
}
#endif

void timerAttach(u08 interruptNum, void (*userFunc)(void) )
{
    // make sure the interrupt number is within bounds
    if(interruptNum < TIMER_NUM_INTERRUPTS)
    {
        // set the interrupt function to run
        // the supplied user's function
        TimerIntFunc[interruptNum] = userFunc;
    }
}

void timerDetach(u08 interruptNum)
{
    // make sure the interrupt number is within bounds
    if(interruptNum < TIMER_NUM_INTERRUPTS)
    {
        // set the interrupt function to run nothing
        TimerIntFunc[interruptNum] = 0;
    }
}
/*
u32 timerMsToTics(u16 ms)
{
    // calculate the prescaler division rate
    u16 prescaleDiv = 1<<(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));
    // calculate the number of timer tics in x milliseconds
    return (ms*(F_CPU/(prescaleDiv*256)))/1000;
}

u16 timerTicsToMs(u32 tics)
{
    // calculate the prescaler division rate
    u16 prescaleDiv = 1<<(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));
    // calculate the number of milliseconds in x timer tics
    return (tics*1000*(prescaleDiv*256))/F_CPU;
}
*/
void timerPause(unsigned short pause_ms)
{
    // pauses for exactly <pause_ms> number of milliseconds
    u08 timerThres;
    u32 ticRateHz;
    u32 pause;

    // capture current pause timer value
    timerThres = TCNT0;
    // reset pause timer overflow count
    TimerPauseReg = 0;
    // calculate delay for [pause_ms] milliseconds
    // prescaler division = 1<<(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)))
    ticRateHz = F_CPU/timer0GetPrescaler();
    // precision management
    // prevent overflow and precision underflow
    //  -could add more conditions to improve accuracy
    if( ((ticRateHz < 429497) && (pause_ms <= 10000)) )
        pause = (pause_ms*ticRateHz)/1000;
    else
        pause = pause_ms*(ticRateHz/1000);

    // loop until time expires
    while( ((TimerPauseReg<<8) | (TCNT0)) < (pause+timerThres) )
    {
        if( TimerPauseReg < (pause>>8));
        {
            // save power by idling the processor
            set_sleep_mode(SLEEP_MODE_IDLE);
            sleep_mode();
        }
    }

    /* old inaccurate code, for reference
    
    // calculate delay for [pause_ms] milliseconds
    u16 prescaleDiv = 1<<(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));
    u32 pause = (pause_ms*(F_CPU/(prescaleDiv*256)))/1000;
    
    TimerPauseReg = 0;
    while(TimerPauseReg < pause);

    */
}

void timer0ClearOverflowCount(void)
{
    // clear the timer overflow counter registers
    Timer0Reg0 = 0; // initialize time registers
}

long timer0GetOverflowCount(void)
{
    // return the current timer overflow count
    // (this is since the last timer0ClearOverflowCount() command was called)
    return Timer0Reg0;
}

#ifdef TCNT2    // support timer2 only if it exists
void timer2ClearOverflowCount(void)
{
    // clear the timer overflow counter registers
    Timer2Reg0 = 0; // initialize time registers
}

long timer2GetOverflowCount(void)
{
    // return the current timer overflow count
    // (this is since the last timer2ClearOverflowCount() command was called)
    return Timer2Reg0;
}
#endif

void timer1PWMInit(u08 bitRes)
{
    // configures timer1 for use with PWM output
    // on OC1A and OC1B pins

    // enable timer1 as 8,9,10bit PWM
    if(bitRes == 9)
    {   // 9bit mode
        sbi(TCCR1A,PWM11);
        cbi(TCCR1A,PWM10);
    }
    else if( bitRes == 10 )
    {   // 10bit mode
        sbi(TCCR1A,PWM11);
        sbi(TCCR1A,PWM10);
    }
    else
    {   // default 8bit mode
        cbi(TCCR1A,PWM11);
        sbi(TCCR1A,PWM10);
    }

    // clear output compare value A
    OCR1A = 0;
    // clear output compare value B
    OCR1B = 0;
}

#ifdef WGM10
// include support for arbitrary top-count PWM
// on new AVR processors that support it
void timer1PWMInitICR(u16 topcount)
{
    // set PWM mode with ICR top-count
    cbi(TCCR1A,WGM10);
    sbi(TCCR1A,WGM11);
    sbi(TCCR1B,WGM12);
    sbi(TCCR1B,WGM13);
    
    // set top count value
    ICR1 = topcount;
    
    // clear output compare value A
    OCR1A = 0;
    // clear output compare value B
    OCR1B = 0;

}
#endif

void timer1PWMOff(void)
{
    // turn off timer1 PWM mode
    cbi(TCCR1A,PWM11);
    cbi(TCCR1A,PWM10);
    // set PWM1A/B (OutputCompare action) to none
    timer1PWMAOff();
    timer1PWMBOff();
}

void timer1PWMAOn(void)
{
    // turn on channel A (OC1A) PWM output
    // set OC1A as non-inverted PWM
    sbi(TCCR1A,COM1A1);
    cbi(TCCR1A,COM1A0);
}

void timer1PWMBOn(void)
{
    // turn on channel B (OC1B) PWM output
    // set OC1B as non-inverted PWM
    sbi(TCCR1A,COM1B1);
    cbi(TCCR1A,COM1B0);
}

void timer1PWMAOff(void)
{
    // turn off channel A (OC1A) PWM output
    // set OC1A (OutputCompare action) to none
    cbi(TCCR1A,COM1A1);
    cbi(TCCR1A,COM1A0);
}

void timer1PWMBOff(void)
{
    // turn off channel B (OC1B) PWM output
    // set OC1B (OutputCompare action) to none
    cbi(TCCR1A,COM1B1);
    cbi(TCCR1A,COM1B0);
}

void timer1PWMASet(u16 pwmDuty)
{
    // set PWM (output compare) duty for channel A
    // this PWM output is generated on OC1A pin
    // NOTE:    pwmDuty should be in the range 0-255 for 8bit PWM
    //          pwmDuty should be in the range 0-511 for 9bit PWM
    //          pwmDuty should be in the range 0-1023 for 10bit PWM
    //outp( (pwmDuty>>8), OCR1AH);      // set the high 8bits of OCR1A
    //outp( (pwmDuty&0x00FF), OCR1AL);  // set the low 8bits of OCR1A
    OCR1A = pwmDuty;
}

void timer1PWMBSet(u16 pwmDuty)
{
    // set PWM (output compare) duty for channel B
    // this PWM output is generated on OC1B pin
    // NOTE:    pwmDuty should be in the range 0-255 for 8bit PWM
    //          pwmDuty should be in the range 0-511 for 9bit PWM
    //          pwmDuty should be in the range 0-1023 for 10bit PWM
    //outp( (pwmDuty>>8), OCR1BH);      // set the high 8bits of OCR1B
    //outp( (pwmDuty&0x00FF), OCR1BL);  // set the low 8bits of OCR1B
    OCR1B = pwmDuty;
}

//! Interrupt handler for tcnt0 overflow interrupt
TIMER_INTERRUPT_HANDLER(SIG_OVERFLOW0)
{
    Timer0Reg0++;           // increment low-order counter

    // increment pause counter
    TimerPauseReg++;

    // if a user function is defined, execute it too
    if(TimerIntFunc[TIMER0OVERFLOW_INT])
        TimerIntFunc[TIMER0OVERFLOW_INT]();
}

//! Interrupt handler for tcnt1 overflow interrupt
TIMER_INTERRUPT_HANDLER(SIG_OVERFLOW1)
{
    // if a user function is defined, execute it
    if(TimerIntFunc[TIMER1OVERFLOW_INT])
        TimerIntFunc[TIMER1OVERFLOW_INT]();
}

#ifdef TCNT2    // support timer2 only if it exists
//! Interrupt handler for tcnt2 overflow interrupt
TIMER_INTERRUPT_HANDLER(SIG_OVERFLOW2)
{
    Timer2Reg0++;           // increment low-order counter

    // if a user function is defined, execute it
    if(TimerIntFunc[TIMER2OVERFLOW_INT])
        TimerIntFunc[TIMER2OVERFLOW_INT]();
}
#endif

#ifdef OCR0
// include support for Output Compare 0 for new AVR processors that support it
//! Interrupt handler for OutputCompare0 match (OC0) interrupt
TIMER_INTERRUPT_HANDLER(SIG_OUTPUT_COMPARE0)
{
    // if a user function is defined, execute it
    if(TimerIntFunc[TIMER0OUTCOMPARE_INT])
        TimerIntFunc[TIMER0OUTCOMPARE_INT]();
}
#endif

//! Interrupt handler for CutputCompare1A match (OC1A) interrupt
TIMER_INTERRUPT_HANDLER(SIG_OUTPUT_COMPARE1A)
{
    // if a user function is defined, execute it
    if(TimerIntFunc[TIMER1OUTCOMPAREA_INT])
        TimerIntFunc[TIMER1OUTCOMPAREA_INT]();
}

//! Interrupt handler for OutputCompare1B match (OC1B) interrupt
TIMER_INTERRUPT_HANDLER(SIG_OUTPUT_COMPARE1B)
{
    // if a user function is defined, execute it
    if(TimerIntFunc[TIMER1OUTCOMPAREB_INT])
        TimerIntFunc[TIMER1OUTCOMPAREB_INT]();
}

//! Interrupt handler for InputCapture1 (IC1) interrupt
TIMER_INTERRUPT_HANDLER(SIG_INPUT_CAPTURE1)
{
    // if a user function is defined, execute it
    if(TimerIntFunc[TIMER1INPUTCAPTURE_INT])
        TimerIntFunc[TIMER1INPUTCAPTURE_INT]();
}

//! Interrupt handler for OutputCompare2A match (OC2A) interrupt
TIMER_INTERRUPT_HANDLER(SIG_OUTPUT_COMPARE2A)
{
    // if a user function is defined, execute it
    if(TimerIntFunc[TIMER2OUTCOMPARE_INT])
        TimerIntFunc[TIMER2OUTCOMPARE_INT]();
}

//! Interrupt handler for OutputCompare2B match (OC2B) interrupt
TIMER_INTERRUPT_HANDLER(SIG_OUTPUT_COMPARE2B)
{
    // if a user function is defined, execute it
    if(TimerIntFunc[TIMER2OUTCOMPARE_INT])
        TimerIntFunc[TIMER2OUTCOMPARE_INT]();
}

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